Grease compostion for automobile electrical equipment auxiliary device and prelubricated rolling using the grease composition

Abstract

To provide a grease composition for auxiliary machinery of automobile electrical component containing an aromatic ester oil-containing base oil having a specific diurea compound as a thickener blended therewith and a rolling bearing having the foregoing grease composition packed therein. The foregoing grease composition and rolling bearing do not generate abnormal noises even at an extremely low temperature of −40° C., have excellent seizure resistance even under a high temperature closed to 180° C., have excellent rust preventing performance, and are suitable especially for electrical parts and auxiliary machineries of engines, etc.

1 . A grease composition for auxiliary machinery of automobile electrical component, which is characterized by containing a base oil containing an aromatic ester oil in an amount of 30% by mass or more based on the whole amount of the base oil and a diurea compound, as a thickener, represented by the following general formula in an amount of from 5 to 35% by mass based on the whole amount of the grease composition: 
         R8-NHCONH—R9-NHCONH—R10 
       (wherein R9 represents an aromatic hydrocarbon group having from 6 to 15 carbon atoms; and R8 and R10, which may be the same or different, each represents an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or a fused ring).  
     
     
         2 . The grease composition for auxiliary machinery of automobile electrical component according to  claim 1 , which is characterized in that the aromatic ester oil is a trimellitic ester oil or a pyromellitic ester oil.  
     
     
         3 . The grease composition for auxiliary machinery of automobile electrical component according to  claim 2 , which is characterized in that in the trimellitic ester oil and the pyromellitic ester oil, a hydrocarbon group to be derived is a hydrocarbon group having from 6 to 10 carbon atoms.  
     
     
         4 . The grease composition for auxiliary machinery of automobile electrical component according to  claim 1 , which is characterized by containing at least one member of carbon black and carbon nano tube as a conductive powder.  
     
     
         5 . The grease composition for auxiliary machinery of automobile electrical component according to  claim 1 , which is characterized by containing two or more members selected from rust preventives made of a carboxylic acid or a carboxylate, ester based rust preventives, and amine based rust preventives in an amount of from 0.2 to 10% by mass in total and from 0.1 to 9.9% by mass singly based on the whole amount of the grease composition.  
     
     
         6 . A rolling bearing, which is characterized by casing freely rollingly plural rolling elements by a cage between an inner race and an outer race and packing the grease composition for auxiliary machinery of automobile electrical component according to  claim 1  therein.  
     
     
         7 . The rolling bearing according to  claim 6 , which is characterized by containing a contact type rubber seal.